         (set-pad-velocity controller x y velocity)
         (aset (:last-grid-pads controller) index velocity)))))
 
+(defn update-effect-list
+  "Display information about the four most recently activated
+  effects."
+  [controller]
+  ;; TODO: Loop over the most recent four active cues, rendering information
+  ;;       about them.
+  )
+
 (defn update-interface
   "Determine the desired current state of the interface, and send any
   changes needed to get it to that state."

  {:pre [(<= 0 line 3)]}
  (midi/midi-sysex (:port-out controller) [240 71 127 21 (+ line 28) 0 0 247]))

(defn- show-labels
  "Illuminates all buttons with text labels, for development assistance."
  ([controller]
   (show-labels controller :bright :amber))

    (reset! (:next-text-buttons controller) {})
    (Arrays/fill (:next-top-pads controller) 0)

    (update-effect-list controller)
    (update-metronome-section controller)

    ;; Reflect the shift button state
